1. Field of the Invention
The present invention generally relates to apparatuses for recording and regenerating data, and more particularly to an apparatus for recording and regenerating data, which apparatus can reduce data regeneration errors caused by a defect of a recording medium or waveform interference between data indicated by a regenerative signal and improve a data generation rate.
Also, the present invention relates to the apparatus for recording and regenerating data which apparatus can eliminate low-frequency noise and high-frequency noise included in a regenerative signal of recorded data and then regenerate the recorded data.
2. Description of the Related Art
Recently, there are many kinds of apparatuses for recording data such as a magnetic disk, a magnetic tape, an optical disk, a magneto-optical disk or the like. A magnetic recording mark is mainly used to record data to these apparatuses. These apparatuses can permanently maintains data more than a semiconductor memory. Thus, since a large amount of data is currently required to process, these apparatus for computers are essential to record graphics and image data for computers.
In a conventional data recording apparatus, data are recorded in accordance with a predetermined format. FIG. 1 is a diagram showing a conventional data format. In the conventional data format, data or data blocks are recorded simultaneously while a VFO area for an AGC (Automatic Gain Control) adjustment and a PLL (Phase-Locked Loop), a Sync-pattern indicating a start of data, or a Resync-pattern for re-synchronizing is inserted. In FIG. 1, these patterns are omitted. In the conventional data recording apparatus, data or data blocks are recorded once on a track or a sector.
FIG. 2 is a diagram showing a conventional circuit configuration for regenerating data recorded in accordance with the data format shown in FIG. 1. In FIG. 2, the conventional circuit configuration is for a most likelihood decode. In the conventional circuit configuration, a BM (Branch Metric) for a sample value 10 obtained by sampling a regenerative signal is calculated at a BM (Branch Metric) calculator 11 and pass metric values are compared at an ACS (Add-Compare-Select) 13. Then, selected pass data is sent to a pass memory 14 and also accumulated in a pass metric memory 12 for a next pass metric calculation. In the pass memory 14, a pass merge occurs and then a most likelihood data is output to a DataOUT 15 as a decoded data. It is called a most likelihood detection known as a decoding method that is strong against noise.
However, since a data recording technology has been developed quickly to record data at higher density, a signal to noise ratio (SNR) is deteriorated by data recorded at higher density. Thus, the data recorded at higher density can not be properly decoded by the conventional most likelihood detection.
Thus, it is desired to improve a regeneration performance for the data recorded at higher density.
It is a general object of the present invention to provide apparatuses for recording and regenerating data in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide an apparatus for recording and regenerating data, which apparatus can reduce data regeneration errors caused by a defect of a recording medium or waveform interference between data indicated by a regenerative signal and improve a data generation rate.
The above objects of the present invention are achieved by a n apparatus for recording and regenerating data, the apparatus including: a recording part iteratively recording the data on a recording medium predetermined times; a sample value storing part storing a sample value obtained by sampling a regenerative signal from the data iteratively recorded on the recording medium; a pass metric calculating part calculating a branch metric and a pass metric based on the sample value stored in the sample value storing part; and a likelihood converting part converting a calculation result obtained by the pass metric calculating part into likelihood of the calculation result, wherein the pass metric calculating part calculates the pass metric based on the likelihood converted by the likelihood converting part and decodes the data recorded on the recording medium.
According to the present invention, it is possible to provide an apparatus in which data is iteratively recorded predetermined times on the recording medium and the likelihood is update every time the same data iteratively recorded on the recording medium is iteratively decoded. Therefore, it is possible to successfully correct a distortion of a regenerative signal caused by a defect of the recording medium.
The above objects of the present invention are achieved by an apparatus for recording and regenerating data, the apparatus including: recording part iteratively recording the data at a data unit dividing the data by a predetermined data length by sequentially changing a predetermined numbers of recording areas on a recording medium; plurality of storage sample value storing parts corresponding to the predetermined numbers of recording areas, respectively, each storage sample value storing part storing a sample value obtained by sampling a regenerative signal from the data recorded on each recording area at the data unit; plurality of pass metric calculating parts corresponding to the plurality of storage sample value storing parts, respectively, each pass metric calculating part calculating a branch metric and a pass metric based on each sample value; plurality of likelihood converting parts corresponding to the plurality of pass metric calculating parts, respectively, each likelihood converting part converting a calculation result obtained by the each pass metric calculating part into likelihood of the calculation result, wherein the each pass metric calculating part calculates the pass metric based on the likelihood converted by the each likelihood converting part and decodes the data recorded on the recording medium.
According to the present invention, it is possible to provide an apparatus in which data is iteratively recorded on the predetermined numbers of recording areas and the data iteratively recorded on the predetermined numbers of recording areas are decoded by the plurality of decoding systems. Therefore, it is possible to decode the same data recorded on the predetermined numbers of recording areas in serial. In addition, the likelihood for the sample value from a previous recording area can effect a next result of the pass metric calculation in accordance with a sampling order of sampling the data recorded on the predetermined numbers of recording area. Therefore, it is possible to reduce the date decoding error caused by the defect of the recording medium.
The above objects of the present invention are achieved by an apparatus for recording and regenerating data, the apparatus including: a recording part recording original data and interleaved data in that a data order of the original data is changed, on the recording medium; a sample storing part storing sample values obtained by sampling regenerative signals from the original data and from the interleaved data recorded in the recording part; a pass metric calculating part calculating a branch metric and a pass metric based on each of the sample values stored in the sample value storing part; and a likelihood converting part converting each calculation result obtained by the pass metric calculating part into likelihood of the each calculation result; and an order changing-back part changing back an data order of the likelihood based on the change of the data order by the recording part, wherein the pass metric calculating part calculates the pass metric based on the likelihood which data order is changed back by the order changing-back part and decodes the data recorded on the recording medium.
According to the present invention, it is possible to provide an apparatus in which the interleaved data, in which the data order of the original data is changed, is recorded on the recording medium and the data order of the likelihood of the original data is changed in accordance with the data order of the interleaved data in order to use for the pass metric calculation for a next interleafed data. Therefore, in a case in which a certain data order causes the interference of the generative signal, it is possible to eliminate noise caused by the interference and then it is possible to obtain more accurate pass metric value.
The above objects of the present invention are achieved by an apparatus for recording and regenerating data, the apparatus including: a recording part converting a first data to be regenerated into a second data in accordance with a predetermined operation and recording the second data; a first decoding part calculating a branch metric and a pass metric as a first calculation result for a sample data by sampling a regenerative signal from the second data recorded on the recording medium and decoding the second data based on the first calculation result; a first likelihood converting part converting the first calculation result into a first likelihood of the first calculation result, the first likelihood corresponding to the first data; a second decoding part generating a synthesized sample value for the first data by a synthesizing process based on the first likelihood, calculating the branch metric and the pass metric as a second calculation result based on the first likelihood, and decoding the second data based on the second calculation result; and a second likelihood converting part converting the second calculation result into a second likelihood of the second calculation result, the second likelihood corresponding to the second data, wherein the first decoding part calculates the pass metric based on the second likelihood converted by the second likelihood converting part, and one of the first data decoded by the second decoding part and the second data decoded by the first decoding part is output as a regenerated data.
According to the present invention, it is possible to provide an apparatus in which the second data, in which the first data as the original data is converted by the predetermined operation, is recorded on the recording medium and the decoding processes for the first data and the second data are conducted after the first data is generated based on the second data recorded on the recording medium. Therefore, it is not required to record the same data many times on a plurality of recording area on the recording medium. Also, it is possible to obtain the likelihood of the first data from the likelihood of the second data that is different from the first data and then decode the first data. Consequently, it is possible to eliminate the data regeneration error derived from the data order of the first data.
The above objects of the present invention are achieved by an apparatus for recording and regenerating data, the apparatus including: a plurality of equalizing parts equalizing a regenerative signal from data recorded on a recording medium by different types of partial responses; a plurality of decoding parts corresponding to the plurality of equalizers, respectively, each decoding part generating likelihood of a sample value of a regenerative signal equalized by each of the plurality of equalizing part, and decoding the sample value; and a decoded data deciding part deciding decoded data based on any one of decoding results by the plurality of decoding parts, wherein each of the plurality of decoding parts decodes the sample value by considering the likelihood generated by one of other decoding parts.
According to the present invention, it is possible to provide an apparatus that can equalize the regenerative signal from the data recorded on the recording medium by the plurality of partial response equalizers reducing different types of noises. Therefore, it is possible to accurately decode the regenerative signal of the data that recorded on the recording medium at high density.